1. Field of the Invention
This invention pertains to the field of smoking materials. More particularly, the present invention concerns a method for preparing a smoking material having reduced tar, nicotine and puff count while still maintaining the desirable characteristics of a smoking material.
2. Description of the Prior Art
It is well known that during the stripping of leaf tobacco in preparation for its use for cigar wrappers or filler, cigarettes and smoking tobacco, a substantial quantity of stems and leaf scraps remains as by-product although some of it has been used for making snuff and for mixture with chewing and smoking tobacco. In addition, there is the tobacco scrap and dust resulting from shipping, handling and other causes. Inasmuch as this so-called by-product is high grade, flavorful tobacco, numerous proposals for its economic use have been made, principally its conversion into the form of synthetic leaf or "reconstituted" tobacco made by adhesively binding finely ground tobacco and forming the mixture into sheets, ribbons, or the like, and substituting the same in whole or in part for natural leaf in cigars, cigarettes, smoking tobacco and other tobacco products. Such techniques are described, for example, in U.S. Pat. Nos. 3,409,026 and 3,386,449.
Although the reconstituted tobacco is made from by-product tobacco, i.e., stems, dust, fines, etc., it nevertheless possesses the same tar, nicotine, and other characteristics associated with natural leaf tobacco. Accordingly, it would be highly desirable to develop a method by which certain constituents of the reconstituted tobacco are reduced while still maintaining the natural flavor and aroma of the tobacco.
Reduction of tar and nicotine in tobacco leaf material has been attempted by incorporating a carbohydrate or cellulosic material which has been thermally degraded in an inert atmosphere (commonly referred to as "pyrolyzed") into the tobacco. Such techniques are disclosed, for example, in U.S. Pat. Nos. 3,545,448; 3,861,401; 3,861,402; and 4,019,521.
Such techniques suffer from many disadvantages. In particular, these techniques require that the pyrolyzed carbohydrate material be blended with the tobacco leaf material while in a dry state. This not only produces a product which is nonuniform, has variable smoking and physical characteristics, but also, produces an undesirable amount of dusting during such processing.
Moreover, this art is specifically directed to, inter alia, reducing the tar and nicotine content of tobacco leaf material and is not at all concerned with combustible reconstituted tobacco as such for use in a smoking material. Reconstituted tobacco in this art is used only to the extent that a solvent extract is made therefrom and the soluble fraction thereof is applied to the pyrolyzed carbohydrate material to impart a tobacco color and aroma. Hence, the art is devoid of any teaching as to the effect of the combustion of pyrolyzed carbohydrate material in conjunction with reconstituted tobacco per se, how such a combination is to be effected (due to the physical characteristics of the particular materials) or what other parameters and variables are involved in order to make a smokable product.
U.S. Pat. No. 3,805,803 discloses a method by which the tar and nicotine content of a reconstituted tobacco smoking materal is reduced. The reduction of these components is accomplished by incorporating activated carbon into the reconstituted tobacco material. The use of carbon, however, presents many disadvantages. In particular, when paper making process is used to produce the reconstituted tobacco, the fine carbon particles interfere with the proper drainage (dewatering) of the tobacco pulp by plugging up the Fourdrinier wire holes or by sticking to the so-called Yankee dryer used to make a paper-like web. It also produces a filler which when used in smoking products introduces an unacceptable off-taste, normally being referred to by those skilled in the art as a "carbon" taste. Moreover, the use of activated carbon in cigarettes produces unacceptable smoking products in that "fiery" particles of glowing charcoal drop off the burning end of a cigarette thus creating a nuisance to the smoker. The "fiery" particles and the "carbon" off-taste are also evident when the material described in U.S. Pat. No. 3,744,496 is used in cigarettes.